Thyroid ☺️

Question 1

Describe the gross structure of the thyroid gland

Answer 1

Under thyroid and cricoid cartilage
R, P, L lobe
Above trachea

Question 2

What are the thyroid hormones
How are they formed
How are they found in the blood
What is the difference between the main 2

Answer 2

TRH => TSH => T3, T4, synthesis
Calcitonin

T4, stable prohormone

• DIT + DIT =thyroid peroxidase=> T4
• TBG, TBPA bound

T3, active metabolite

• DIT + MIT =thyroid peroxidase=> T3
• T4 also metabolized in periphery
• TBG, albumin bound

Calcitonin
-released by increased [Ca] plasma

T3, 4 negative feedback on HPA

Question 3

What are the main functions of the thyroid

Answer 3

Increase NAKATPase => 
increase aerobic respiration
Increase cardiac contractility
Increase temperature
Increase gut motility
Increase bone, protein, hormone turnover

Question 4

What is a goiter

-what are the 2 situations where it would form

Answer 4

Increased hyperplasia, hypertrophy of gland

• insufficient I2 in diet/goitrogens => unable to make enough T3, 4
• excess follicular cell stimulation => too much T3, 4 synthesis

Question 5

What is the difference between hyperthyroidism and thyrotoxicosis

Answer 5

Hyperthyroidism
-Thyroid is secreting too much thyroid hormone

Thyrotoxicosis
-Too much thyroid hormone in the circulation, irrespetive of source

Question 6

What are the symptoms of hyperthyroidism

Answer 6

Weight loss
AF
Sweating, heat intolerance
Pretibial myxodema, thyroid acropachy 
Diarrhoea 
Oligomenorrhea
Anxiety, tremor

Question 7

What investigations are indicative of

• thyrotoxicosis (Graves)
• 1ary hypo (Hashimotos)
• 2ndary hypo
• sick euthyroid
• subclinical hypo
• poor compliance with thyroxine

Answer 7

Thyrotoxicosis - low TSH, high T3,4

• Graves - TSH receptor AB (exophthalmos, pretibial myxedema, graves acropathy)
• Toxic multinodular goitre
• Amiodarone

Primary hypo - high TSH, low T3,4

• Hashimotos - goitres TPO AB
• Atrophic - no goitre
• Subacute thyroiditis/de Quervians - painful goitre, high ESR
• Riedel’s fibrous thyroiditis - painless goitre
• Postpartum
• Lithium, amiodarone
• Iodine deficiency

Secondary hypo - low TSH, low T3,4
-sick euthyroid syndrome - self limiting

Subclinical hypo - high TSH, normal T3,4
-TSH more sensitive to thyroid issues,
Poor compliance with thyroxine - high TSH, normal T3,4
-TSH reflects long term thyroid function

Thyroid uptake scan via nuclear scintigraphy, ultrasound

Question 8

Thyrotoxicosis management

Answer 8

Propanolol - symptom management
1st line Carbimazole (or propylthiouracil) - blocks TPO, reduce T3,4 prod

Radioiodine treatment
Surgery to remove nodule

Question 9

Presentation of hypothyroidism

Answer 9

Weight gain
Dry, yellow skin
Non pitting edema
Dry coarse scalp hair, loss of lateral eyebrow hairs
Constipation
Menorrhagia
Decreased deep tendon reflexes, carpal tunnel

DUE TO DECREASED METABOLISM

Question 10

Management of hypothyroidism

Answer 10

T4, levothyroxine (FIRST LINE)

T3, liothyroxine

Question 11

Thyroid nodule investigations and presentation
Differentiate between a benign and malignant nodule
Types

Answer 11

Goitre
May be non functional, hypo, hyper
-generally normal

USS, fine needle aspiration
-check for malignant cells

Benign => conservative interval scan
Malignant => lobectomy, thyroidectomy
-papillary - best prognosis, most common
-follicular 
-medullary - C cells affected, part of MEN2
-anaplastic - 
-lymphoma - linked to Hashimotos

Question 12

3 forms of painless thyroiditis
2 forms of painful thyroiditis
What characteristic is common between these types

Answer 12

Lymphocytic (AI, Hashimoto)
Postpartum
Riedel’s (fibrous)

De Quervains (granulomatous)
Radiation induced

Can flip flop between hyper, eu and hypothyroid states